Snap-lock base for annular fluorescent lamps

ABSTRACT

The invention relates to a base for annular fluorescent lamps, preferably for lamps provided with metal end caps. The base comprises two thin-walled semi-cylindrical parts that are molded from resilient plastic and are shaped to interlock with a snapfit. One of the base parts carries four metallic contact pins and the other serves as a cover for the lead-in wires and the end portions of the lamp envelope. The snap-fitting portions of the base parts are so shaped that the base can be reopened with a special tool. The base also provides a chamber that is large enough to accommodate exhaust tubulations that would otherwise be too long or eccentric.

[ Dec. 31, 1974 SNAP-LOCK BASE FOR ANNULAR FLUORESCENT LAMPS [75] Inventors: Giinter Mai; Herbert Pietzsch, both of Munich, Germany [73] Assignee: Patent-Treuhand-Gesellschalt fur elektrische Gluhlampen mbH, Munich, Germany [22] Filed: May 9, 1973 [21] App]. No.: 358,790

[30] Foreign Application Priority Data May 19, 1972 Germany 7218982 [52] U.S. Cl 339/145 D, 339/52, 339/208 [51] Int. Cl H011 33/74 [58] Field of Search 339/50, 57, 145 R, 145 D, 339/206 L, 208, 209, 210, 189, 128, 191 F,

2,597,666 5/1952 Oday et al. 339/145 D 2,626,977 l/1953 Hinman 339/145 D 2,733,417 l/l956 Hinman et al. 339/50 C 2,802,191 8/1957 Nicolaro 339/ 145 3,471,825 10/1969 Huber 339/128 Primary Examiner--Roy D. Frazier Assistant Examiner-Robert A. Hafer Attorney, Agent, or FirmD. S. Buleza 5 7] ABSTRACT The invention relates to a base for annular fluorescent lamps, preferably for lamps provided with metal end caps. The base comprises two thin-walled semicylindrical parts that are molded from resilient plastic and are shaped to interlock with a snapfit. One of the base parts carries four metallic contact pins and the other serves as a cover for the lead-in wires and the end portions of the lamp envelope. The snap-fitting portions of the base parts are so shaped that the base can be reopened with a special tool. The base also provides a chamber that is large enough to accommodate exhaust tubulations that would otherwise be too long or eccentric.

8 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a base for an electric lamp and has particular reference to a two-piece base for a fluorescent lamp of annular configuration.

2. Description of the Prior Art Bases for so-called circleline fluorescent lamps are designed to bridge the free space between the two ends of the lamp envelope and form a closed annular ring. Protection from electric shock hazards is provided by covering the lead-in wires and the lamp is designed to fit into the socket in a predetermined position.

Bases of this type consisting of two or more component parts which are joined by screws and can thus be reopened as desired are well known in the art. In the most commonly used, centrally disposed screw-type connection is employed, as shown in US. Pat. No. 2,413,662. Since the connection fills part of the base interior the exhaust tube of the fluorescent lamp must be short enough to fit into the interior of the base. Posttreatment of the exhaust tube is thus often required to shorten it.

The same problem is generally encountered in bases where the component parts are joined by a single rivet instead of by a screw (as in Japanese Utility Model 4020-] 24).

Though a relatively free interior chamber is provided in prior art bases where the component parts are joined by a plurality of rivets (as disclosed in US. Pat. No. 2,733,417), it is not possible to reopen such riveted bases without destroying them.

The base structure in accordance with U.S. Pat. No. 2,453,986 includes, among other things, means for protection from distortion or displacement relative to the lamp. Due to the screw plug, there is, however, no hollow space left in the base. Furthermore, since the contact pins of such bases are inclined 30 relative to the annular plane, these bases do not meet the socket standards established in Europe, for example, which require that the contact pins be inclined 45 relative to the annular plane.

In addition to the aforesaid screw-fitted and riveted bases, base types which have a snap-fit closure are also known (see Jap. Utility Model 46-15-989). However, this type of closure does not permit a reopening of the mounted base. Due to the design of the snap-fit closure, a small hollow chamber is provided in the base interior but the length of the chamber is quite limited. The bottom carrying the contact pins is only slightly recessed in the outer wall of the base. Thus, connections between such bases and sockets which meet the aforesaid standards do not guarantee protection from electric shock hazards. Moreover, this type of base has no means for protection from displacement and distortion.

SUMMARY OF THE INVENTION An object of the present invention is to provide a base for annular fluorescent lamps, preferably lamps having metal end caps, which meets the aforesaid standards as regards pin orientation and permits the basing of annular lamps that have long tipped-off exhaust tubes which also enables the bases of defective lamps to be removed and salvaged.

The foregoing objectives are achieved by making the base in two component parts that are joined by a snapfit closure without any screws or rivets in a manner such that the closed base can be reopened with a special tool, that the two joined semi-cylindrical base parts provide a long hollow chamber, that the bottom of one of the base parts which carries the contact pins projects into the chamber a length such that the lead-in wires are spaced a sufficient distance from the metal end caps of the lamp, and that the base is protected from distortion and displacement relative to the lamp.

In addition, the bottom segment which carries the contact pins is recessed in the base wall and the contact pins are riveted into this segment. The latter is preferably square-shaped and the base parts are preferably molded from a high-temperature resistant and resilient plastic.

The snap-fit closure is formed by flaps which are so located in the base wall that the interior of the base is substantially unobstructed. This permits a larger tolerance in the manufacture of the exhaust tube of the annular lamp with regard to its length and to the angle which is formed between the exhaust tube and the lamp axis. Consequently, the previously required posttreatment of the exhaust tube can be omitted, and manufacture of the lamp is rendered less expensive.

Since the final test of the finished lamps takes place with the bases already mounted, a great advantage of the invention is the possibility to reopen the snap-fit closure with the aid of a tool and to detach the base again from a defective lamp in order to reuse the base. Protection from distortion and displacement of the base is achieved by short longitudinal ribs and semicircular transverse ribs. The arrangement of the contact pins with regard to the annular plane as well as the optimum recessing of the bottom which carries the contact pins are such that the base is adapted to European socket standards. The improved base encloses the leadin wires and lamp end portions provided with metallic end caps and thus provides protection from electric shock hazards. Moreover, opening of the base is only possible when the base is not inserted in a socket.

Since the bottom segment of the base which carries the contact pins projects a sufficient length into the base interior, the lead-in wires cannot contact the end caps and therefore need not be electrically insulated.

BRIEF DESCRIPTION OF THE DRAWING An exemplary embodiment of the invention is shown in the accompanying drawings wherein:

FIG. 1 is a perspective view of the base parts in opened condition;

FIG. 2 is a plan view of the base in closed condition; and

FIG. 3 is a side elevational view of the closed base, partly in section.

DESCRIPTION OF THE PREFERRED EMBODIMENT The base structure is adapted to the arc shape of an annular fluorescent lamp. As shown in FIG. 1, the two base parts 1 and 2 accordingly each have a longer Iongitudinal edge 3 and 4, respectively, and a shorter longitudinal edge 5 and 6, respectively. The covering flap 7 of the longitudinal edge 3 and the recessed flap 8 of the longitudinal edge 4, as well as the covering flap 9 of the longitudinal edge 5 and the recessed flap 10 of the longitudinal edge 6, form the two pairs of interlocking flaps.

The inner sides of the covering flaps 7 and 9 are each provided with a short longitudinal rib 11 and the recessed flaps 8 and are each provided with a wedge 12. The wedges 12 each have a flattened end portion 13 that projects beyond the front edges 14 of the recessed flaps 8 and 10. The elevated wedge end portions 15 steeply drop toward the exterior surfaces of respective flaps 8 and 10. The covering flaps 7 and 9 have reinforced lateral edges 16. Accordingly, the width of wedge 12 is reduced with regard to the respective recessed flaps 8 and 10 by the total width of the two lateral edges 16. The reinforced lateral edges 16 thus form a strutting for the covering flaps 7 and 9. Furthermore, they prevent a misalignment of the two semicylindrical base parts with regard to one another, since the exterior lateral faces of 16 closely abut the faces 17 of flaps 8 and 10.

The front edge of the covering flap 7 of the longitudinal edge 3 is provided with a small recess 18 that defines a notch-like opening.

Two semi-circular transverse ribs 20 extend along the inner surface of base wall 19 of the base part 1. Since the bottom segment 21 which carries the contact pins is recessed in the base wall 19 of the other base part 2 from outside, the square-shaped recess forms a corresponding elevation in the chamber 22 defined by the base. In closed condition of the base, the side walls 23 of said elevation together with the transverse ribs 20 form buffers for the metal end caps of the tubular ends of the lamp envelope. Straps 24 which are provided with a slightly arc-shaped bulging and are suited in front of side walls 23 serve as a support for the end caps. The bottom segment 21 projects into the base chamber 22 a length such that the lead-in wires cannot get into contact with the end caps of the lamp.

As illustrated in FIG. 2, the covering flaps 7 and 9 of base part 1 (only flap 7 with recess 18 is shown) fit into the rectangular recesses in the exterior base wall 19 and form a smooth continuous surface with base part 2. The contact pins 25 are riveted into bottom segment 21 which is recessed in the base wall 19 from outside, I

or they are secured thereto by ultrasonic techniques.

The sectional view shown in FIG. 3 through one of the interlocked pairs of flaps 9, 10 illustrates the closing mechanism. Between the flattened end 13 of wedge 12 and the elevated wedge end 15 of base part 2 there is a tapered surface over which the rib ll of base part 1 is obliged to slide when the base parts are pressed together and the pairs of flaps are closed. The parts 1 and 2 are elastically widened during this operation so that, after passing across the steeply dropping elevated wedge end 15, the longitudinal rib 11 snaps behind 15 and comes to rest on the surface of the recessed flap 10. The elastic base thereby resumes its original shape.

The transverse ribs 20 of base part 1 project only slightly into the base interior so that a large hollow chamber 22 is formed. The side walls 23 of bottom segment 21 of base part 2 which carries the contact pins 25 project slightly further into the chamber. The base walls 19 of both base parts 1 and 2 are quite thin and of substantially uniform thickness, as shown in FIGS. 1 and 3.

Another section immediately behind one of the transverse ribs 20 (see FIG. 3) shows the two short longitudinal ribs 26 which extend up to said transverse rib 20 along the inner surface of the wall 19 of base part 1. These longitudinal ribs 26, between which the locking tab secured to the respective end caps is situated, afford protection of the base from distortion relative to the lamp.

The closed base can be readily opened by introducing a special tool into the recess 18 of covering flap 7. By lifting flap 7, the longitudinal rib 11 is lifted over the elevated wedge end 15. The two base parts can then be separated from one another.

We claim as our invention:

1. A base for an annular fluorescent lamp having an envelope with a protruding exhaust tube, said base comprising;

a pair of generally semicylindrical-shaped components of resilient insulating material having integral interfitting portions operable to lock said component together in closed abutting relationship solely by means of a snap-fit, one of said base components having an inwardly-recessed segment which carries a plurality of contact pins,

each of said base components having walls of such thickness and being of such configuration that they define, when snap-fitted together in assembled relation, a chamber of sufiicient size to accommodate the ends of the lamp envelope and exhaust tube despite variations in the length and alignment of said exhaust tube,

said interfitting portions comprising a pair of covering flaps that laterally project beyond the longitudinal edges of one of said base components and a pair of mating recessed flaps that laterally project beyond the longitudinal edges of the other of said base components and define recesses in the exterior wall thereof which are shaped and dimensioned to receive and accommodate said covering flaps,

one of said covering flaps having a notch-like opening in its longitudinal edge through which the base components can be mechanically separated from snap-fitted relationship with one another, and

said covering flaps being of such configuration that they form a substantially smooth exterior surface with the base component having the recessed flaps, when said base components are snap-fitted together and said covering flaps are seated in said recesses.

2. A base in accordance with claim 1 wherein the walls of said base components are of substantially uniform thickness and said pair of covering flaps and said pair of recessed flaps are so located on the associated base walls that the interior of the assembled base is substantially unobstructed.

3. A base in accordance with claim 2 wherein; a longitudinal rib is disposed on the inner side of each of said covering flaps, and each of said recessed flaps has a wedge-shaped element that is disposed to engage and interlock with one of said ribs when the base components are pressed together.

4. A base in accordance with claim 3 wherein each of said covering flaps have reinforced lateral edges that are spaced to accommodate the wedge-shaped elements of said recessed flaps.

5. A base in accordance with claim 3 wherein said wedge-shaped elements each have a tapered surface that is slidingly engaged by and coacts with the longitudinal ribs of the covering flaps to temporarily deform therespective base components during the snap-fitting longitndinal reinforcing ribs extend on the inside wall of said base component between said transverseribs.

8. A base in accordance with claim 1 wherein each of said base components are composed of a resilient high-temperature resistant plastic. 

1. A base for an annular fluorescent lamp having an envelope with a protruding exhaust tube, said base comprising; a pair of generally semicylindrical-shaped components of resilient insulating material having integral interfitting portions operable to lock said component together in closed abutting relationship solely by means of a snap-fit, one of said base components having an inwardly-recessed segment which carries a plurality of contact pins, each of said base components having walls of such thickness and being of such configuration that they define, when snap-fitted together in assembled relation, a chamber of sufficient size to accommodate the ends of the lamp envelope and exhaust tube despite variations in the length and alignment of said exhaust tube, said interfitting portions comprising a pair of covering flaps that laterally project beyond the longitudinal edges of one of said base components and a pair of mating recessed flaps that laterally project beyond the longitudinal edges of the other of said base components and define recesses in the exterior wall thereof which are shaped and dimensioned to receive and accommodate said covering flaps, one of said covering flaps having a notch-like opening in its longitudinal edge through which the base components can be mechanically separated from snap-fitted relationship with one another, and said covering flaps being of such configuration that they form a substantially smooth exterior surface with the base component having the recessed flaps, when said base components are snapfitted together and said covering flaps are seated in said recesses.
 2. A base in accordance with claim 1 wherein the walls of said base components are of substantially uniform thickness and said pair of covering flaps and said pair of recessed flaps are so located on the associated base walls that the interior of the assembled base is substantially unobstructed.
 3. A base in accordance with claim 2 wherein; a longitudinal rib is disposed on the inner side of each of said covering flaps, and each of said recessed flaps has a wedge-shaped element that is disposed to engage and interlock with one of said ribs when the base components are pressed together.
 4. A base in accordance with claim 3 wherein each of said covering flaps have reinforced lateral edges that are spaced to accommodate the wedge-shaped elements of said recessed flaps.
 5. A base in accordance with claim 3 wherein said wedge-shaped elements each have a tapered surface that is slidingly engaged by and coacts with the longitudinal ribs of the covering flaps to temporarily deform the respective base components during the snap-fitting operation.
 6. A base in accordance with claim 1 wherein the base component that is devoid of contact pins has a pair of transverse reinforcing ribs of semi-circular configuration on its inner surface.
 7. A base in accordance with claim 6 wherein two longitudinal reinforcing ribs extend on the inside wall of said base component between said transverse ribs.
 8. A base in accordance with claim 1 wherein each of said base components are composed of a resilient high-temperature resistant plastic. 